Highly Efficient Fabrication of Polymer Nanofiber Assembly by Centrifugal Jet Spinning: Process and Characterization

Centrifugal jet spinning (CJS) is a highly efficient, low-cost, and versatile method for fabricating polymer nanofiber assemblies, especially in comparison to electrospinning. The process uses centrifugal forces coupled with the viscoelastic properties and the mass transfer characteristics of spinning solutions to promote the controlled thinning of a polymer solution filament into nanofibers. In this study, three different spinning stages (jet initiation, jet extension, and fiber formation) were analyzed in terms of the roles of fluid viscoelasticity, centrifugal forces, and solvent mass transfer. Four different polymer solution systems were used, which enables a wide range of fluid viscoelasticity properties and solvent mass transfer properties, and polymer fibers were fabricated under different rotational speeds for these polymer solutions. The key dimensionless groups that determine the product morphology (beads, beads-on-fiber, and continuous fiber) and the radius of the fiber (when fibers are formed) were identified. The obtained morphology state diagram and fiber radius model were tested using a fifth polymer solution system. Results indicate that Weissenberg number and capillary number are important during the fiber extension stage to enable fiber formation while the elastic processability number is the determinative dimensionless number for fiber diameter prediction.